An extension to the NHLBI Growth and Health Study (NCHS), a seven-year cohort study of the development of obesity and its effects on cardiovascular disease risk factors in 2 ,379 black and white adolescent females, is proposed to continue follow-up of the cohort until subjects reach early adulthood, a time when lifelong patterns of health-related behaviors are established. In prepubertal subjects, there were no significant race differences in body composition or blood pressure and black girls had lower LDL-cholesterol and triglycerides and higher HDL- cholesterol. By ages 13-14, black females weighed significantly more and had significantly larger skinfold thicknesses and circumferences than white females. However, these changes were not accompanied by concomitant changes in CVD risk factors known to be strongly associated with obesity: at ages 13-14, black girls still had higher HDL-cholesterol and lower triglycerides and racial differences in blood pressure were not consistently significant. Data from CARDIA indicate that at ages 18-24, black females had significantly higher blood pressure and LDL-cholesterol. This suggests that obesity-related changes in CVD risk factors will occur in the late adolescent-early adulthood period. Only a longitudinal study spanning this period can explain the increased CVD risk in black women observed by early adulthood. NGHS III will follow this cohort of girls until they have reached early adulthood (ages 19-20). Specifically, NGHS III will examine: l) changes in weight, body fat and fat distribution; 2) changes in dietary intakes and physical activity patterns; 3) changes in blood pressure and blood lipids; 4) fasting glucose and insulin levels; 5) psychosocial factors (e.g., self-concept, stress, coping, dietary practices and attitudes and beliefs about body image and weight); 6) occurrence of smoking and alcohol use; 7) pregnancy. Continued follow-up of the NGHS cohort will yield important scientific information for improving women's health by potentially identify areas for practical interventions to prevent obesity and its related sequelae.